I want to make THIS cake from Wilton, but near the bottom, it talks about attaching the ribbon strips with thinned fondant. What is that? What do I thin the fondant with?

TIA,
Z

You can make a sort of glue by dissolving fondant in water. Gumpaste works better for this, even better yes is dissolving CMC or tylose to make your glue. You can also use plain water to glue fondant.